This invention relates to improvements in safety mechanisms for firearms; and, especially, to improvements in safety mechanisms employing means maintaining the firearm in a "safe" position by blocking movement of the firing pin and/or by blocking movement of the trigger or sear.
A typical conventional safety mechanism of the type to which the invention has application is shown in Walker et al U.S. Pat. No. 2,514,981. The Walker mechanism has a safety pivotally mounted for rotation about a pivot pin for bringing a bolt lock arm portion up into bolt movement blocking position within a notch in the bolt, while simultaneously bringing the eccentric end of an inner arm portion into sear movement blocking position with the heel of a sear safety cam. The details of such a conventional system are set forth in that patent, incorporated herein by reference, and the reader is referred thereto for additional background.
The Walker and similar safety mechanisms function by moving between two positions: a "safe" position in which the bolt and sear (or trigger) are blocked, and a "fire" position in which the bolt and sear are unobstructed. Movement from one position to the other is normally accomplished by manual rotation of an elongated lever arm portion (typically having an enlarged head of some kind) of the safety, that projects upwardly to the outside of the firearm to a position easily accessible by the thumb of the shooter. In a typical such arrangement, a ball detent loosely seated in a hole formed in the bolt lock arm portion of the safety is biased by means of a leaf spring into alternative engagement with one of two detent holes formed in the side wall of the trigger housing to releasably detain the safety in its desired one of the two positions.
The redundancy afforded by having both bolt blocking and sear blocking means, as in the Walker mechanism, is helpful so that inadvertent pressing of the trigger while the safety is in the "safe" position will not condition the firearm to subsequently fire as soon as the safety is released. Such two-position mechanisms, however, have the disadvantage that the bolt cannot be drawn back to unload the weapon or remove the bolt without first placing the safety in the "fire" position to release the bolt lock arm portion.